Field



No. 749,705. PATENTED JAN. 12, 1904. F. 0. $0HOFIELD. REGULATOR FORINGANDESCENT LAMP S.

APPLIUATION FILED MAY 7, 1903.

N0 MODEL.

El wuantoz UNITED STATES Patented January 12, 1904.

PATENT OFFICE.

REGULATOR FOR INCANDESCENT LAMPS.

SPECIFICATION forming part of Letters Patent No. 749,705, dated January12, 1904:.

Application filed May '7, 1903. Serial No. 156,097. (No model.)

To all whmn it may concern.-

Be it known that I, FREDERIOK C. Sono- FIELD, a citizen of the UnitedStates, residing at Washington, District of Columbia, have inventedcertain new and useful Improvements in Regulators for IncandescentLamps; and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same.

This invention relates more especially to that class ofincandescent-electric-lamp regulators which employ a rheostat to varythe intensity of the light by varying the currentfiow through the lampand is adapted for use upon either an alternating or direct currentcircuit.

My present invention further constitutes an improvement upon theregulator disclosed in United States Patent No. 686,910, granted to meNovember 19, 1901, and in this respect relates particularly to the modeof winding and connecting of the resistance-coil and the manner ofmounting the same, whereby a more improved form of rheostat and betterventilation of the same are obtained.

My invention further consists in the novel combination and arrangementof parts hereinafter described, and particularly pointed out in theclaims.

Referring to the accompanying drawings, which form a part of thisspecification and which illustrate an embodiment of my invention, Figure1 represents in elevation an incandescent electric lamp provided with myimproved regulator; Fig. 2, an enlarged view showing the rheostat inelevation and the outer casing in central vertical section; Fig. 3, abottom plan view of the regulator with the lower retaining cap removed,showing the movable switch in position; Fig. a, a similar view of theregulator with the movable switch removed to show the switch-contacts;Fig. 5, a perspective View of the movable switch, and Fig. 6 a diagramof the electric circuits of the regulator.

Similar numerals refer to similar parts throughout the several views, inwhich 1 represents the resistance-coil,wound, preferably, in one layerupon a sheet-iron or other metal cylinder 2, the said cylinder beingsuitably insulated from the coil by a coating of paper or otherinsulating material. This cylinder, however, may be of porcelain orother suitable insulating material.

The cylinder 2 is held between two heads or collars 3 and I, ofporcelain, vulcanite fiber, or other suitable insulating material, whichheads are provided with annular grooves 5 and 6, respectively, intowhich the ends of the cylinder 2 fit. For the purpose of admitting afree circulation of air through the cylinder 2, and consequently coolingthe rheostat, the ends of the cylinder are serrated, so as to form aseries of openings 7.

The heads 3 and 4 are each provided with a central aperture, throughwhich passes a brass or other suitable metal tube 8, slightly flared atone end, as at 9, to provide a shoulder or stop for the head 3, andscrew-threaded, as at 10, to receive a nut 11, which securely clamps theheads 3 and I against the ends of the cylinder 2.

The rheostat is inclosed in a suitable brass or other metal casingconsisting of a sheathing 12, which fits over the heads 8 and 4:, anupper cap 13, having an opening at its top to admit the lamp-cord orfeed-wire, and a lower cap or head 14, which is held between the head tand nut 11. The sheathing 12 is provided with adouble series of openings15 for the purpose of ventilation.

The socket 16 of the lamp is adapted to screw on the lower end of thetube 8, through which tube the cord or feed-wires pass to the lamp.

The resistance-coil 1 of the rheostat consists of a single conductor ofinsulated German silver or other suitable wire doubled upon itself, soas to form a loop 17 at one end (see Fig. 6) and wound in two parallelstrandsthatis, non-inductivelypreferably in a single layer terminatingin the ends 18 19, which are connected to two terminal binding screws orcontacts 20 and 21, respectively, mounted upon the insulating collar orhead 3. The contact 21 connects direct to one of the feed-wires of thelamp-circuit, and the other contact 20 to the lamp-socket. (See Fig. 6.)

In an annular recess 22 in the lower face of the head 4 are fourswitch-contacts 23 24 25 26, consisting of metal pins which pass throughthe head 4 and terminate slightly above its upper face. The contacts 23and 24 are connected, respectively, by conductors 27 and 28 direct tothe terminal contacts 20 and 21.

At a suitable point in the resistance-coil one of the strands is loopeddown, as at 29, and connected to switch-contact 25, while at anotherpoint in the resistance-coil the other strand is looped down, as at 30,and connected to the contact 26, there beingno breakin theresistance-coil. Obviously more points in the coil may be similarlyconnected to other switchcontacts; but the number shown is sufficient todisclose the principle of my invention. This mode of looping theresistance-coil down to the contacts obviates the necessity ofconnecting leads from the contacts to the coil, which connections haveto be soldered and are extremely troublesome to make and always impairthe insulation.

By connecting the switch-contacts in certain combinations I may eithershunt the resistance-coil altogether and allow the full current to flowthrough the lamp, may vary the amount of resistance in series with thelamp, and thereby vary the intensity of the light by connecting in partof the resistance-coil, or may connect all of the resistance-coil inseries with the lamp and obtain a maximum dimness of light withoutentirely extinguishing it. For thus connecting together the contacts 23to 26 I provide a movable switch 31, consisting of a thin metal ringresilient in character and mounted in the annular recess 22. This switch31 is provided with an offset portion 32 of sufficient length to bridgethree of the switchcontacts at a time and is slightly sprung, as at 33,so that it will be held against the switchcontacts under tension by thecap 14, which engages it. Bymeans of the friction thus created theswitch will remain in the position without further provision. The switchis operated by means of a handle 34, which extends through an opening inthe flange surrounding the annular space in which the switch is located.

Referring to the diagram Fig. 6, it will be seen that when the switch isturned to that position Where it bridges contacts 23, 24, and 25 thecurrent from the positive terminal contact will take the followingcourse: conductor 28, contact 24, switch 31, contact 23, conductor 27through the lamp. In this case the Whole coil of the rheostat is shuntedand the full current passes through the lamp. Now suppose the switch ismoved to the next step, so that it bridges contacts 24, 25, and 26. Thecurrent will then pass from the contact 21 to conductor 28, contact 24,switch 31, contact 25, loop 29, and thence through a certain length ofthe resistance-coil to the lamp. This inserts a certain amount of extraresistance in the lamp-circuit, and thus dirns the light.

If it is desired to dim the light still further, more resistance can beintroduced by shifting the switch so that it bridges contacts 25 and 26.In this position of the switch the current takes the following course:from contact 21 through the resistance-coil to loop 30, then throughcontact 26 to contact 25, loop 29, an other portion of theresistance-coil, and thence to the lamp.

If it is desired to insert the entire resistance of the coil 1 in thelamp-circuit, the switch is shifted still farther until it rests uponthe contact 26 only.

By the foregoing arrangement I secure a lam p-regulatin g rheostat whichis simple, comparatively inexpensive, and easy of manufacture, and whichis eflicient to a high degree.

Having thus described my invention, what I claim is 1. In anelectric-lamp regulator, the combination with a central tube, of ahollow core surrounding said tube and forming an airspace around thesame, heads supporting said core at each end thereof and mounted on saidtube, a resistance-coil wound on said core, and means for connectingvarying amounts of said coil in the lamp-circuit.

2. In an electric-lamp regulator, the combination with a centrzl tube,of a hollow core surrounding said tube and forming an airspacetherearound, s 'd core having serrated ends, heads supporting said coreat each end and mounted on said tube, a resistance-coil wound on saidcore, means for connecting varying amounts of resistance in thelampcircrit, a casing surrounding said coil and provided viii a seriesof openings, and a cap adapted to fit over the upper end of said casingand head of said core.

3. In an electric-lamp regulator, the combination with an incandescentelectric lamp and socket, of a tube through which the main lamp-wirespass, and connected to the lampsoclzet, a hollow core surrounding saidtube and forming an air-space around the same, heads supporting saidcore at each end and provided each with a central opening through whichsaid tube passes, extending longitudinally through said core, aresistance-coil wound on said core, and a switch having contactsconnected to sections of said coil and to the lampcircuit direct forvarying the resistance of said circuit.

4. In an electric-lamp regulator, the combi nation with a tube throughwhich the main lamp-wires pass, of a hollow core surrounding said tube,forming an air-space therearound and provided with a series of sideopenings around each end, heads supporting said core at each end andmounted upon said tube which passes through said heads andlongitudinally through the said core, a resistancecoil on said core, andmeans for connecting varying amounts of said coil in the lamp-circuit.

5. In an electric-lamp regulator, the combi- IIO nation with a centraltube, of a hollow core surrounding said tube and forming an airspacetherearound, heads of insulating material supporting said core at eachend thereof and mounted on said tube, a resistance-coil wound on saidcore and adapted to connect to the lamp-circuit, a series ofswitch-contacts, mounted on one of the heads of said core, adapted toconnect to said lamp-circuit and to points in the length of saidresistance-coil, and a moving switch comprising a conductor adapted topass over and in contact with said switchcontacts.

6. In an electric-lamp regulator, the combination with aresistance-coil, of a series of switch-contacts, a series of loops eachforming a continuation of the resistance-conductor, and each loopconnected to an individual switchcontact, and a movable switch adaptedto engage said contacts and electrically connect the same.

7 In an electric-lamp regulator, the combination with anincandescent-electric-lamp circuit, of aresistance-coil connectedthereto, and means for supporting said coil, a series ofswitch-contacts, conductors connecting two of said contacts to thelamp-circuit, and forming a shunt around the resistance-coil, and loopsforming continuations of the resistance-conductor located at intervalsin the length of said conductor and each loop connected to an individualswitch contact, and a movable switch adapted to connect said contactstogether in combinations whereby the said resistance coil may be shuntedor various amounts thereof connected in the lamp-circuit.

8. In an electric-lamp regulator, the combination with aresistance-coil, of a core upon which said coil is wound, headssupporting said core at each end, one of said heads having an annulargroove formed on one of its faces, a series of switch contacts locatedin said groove and connected to points in the length of saidresistance-coil, a movable metal ring mounted in said annular groove andforming a switch for connecting together said contacts in variouscombinations.

9. In an electric-lamp regulator, the combination with aresistance-coil, of a head forming a part of the support therefor, andhaving an annular groove in one of its faces, a series ofswitch-contacts located in said groove, a resilient bowed metal ringmovable around in said groove and provided with an offset portionadapted to engage said contacts, and a cap bearing on said bowed ringwhereby the same is held in position under tension.

10. In an electric-lamp regulator, the combination of a hollow core, theends thereof being cut away so as to leave projecting portions andspaces between said portions for the purpose of ventilation, aresistance-coil mounted on said core, said resistance-coil beingcomposed of two strands connected in series with the lamp, said strandsbeing wound around said hollow core parallel to each other andterminating in a loop, whereby the inductive effect of an electriccurrent is neutralized, and means for connecting varying amounts of saidcoil in the lamp-circuit.

In testimony whereof I affix my signature in presence of two witnesses.

FREDERICK C. SCHOFIELD.

Witnesses:

C. W. FOWLER, THEODORE DALTON.

